<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body >
<div>
    <div id="top" style="background-color: azure;height: 50px"align="center">
            黑马在线教育系统
    </div>
    <div id="left"  style="width:100px; height: 800px; float:left; background-color: bisque" align="center" >
        左侧菜单
        <table >
            <tr><td><a href="1.html" target="content">菜单1</a></td></tr>
            <tr><td>菜单2</td></tr>
            <tr><td>菜单3</td></tr>
        </table>
    </div>
    <div id="right" align="center" style="margin: 0">
        <iframe  name="content" src="default.html" height="800px" width="90%" style="border: 0">

        </iframe>
    </div>
</div>
</body>
</html>